Feasibility of manufacturing antimicrobial system containing garlic (Allium sativum L.) aqueous extract through electrostatic interaction method in gelatin- Persian gum complex

Abstract

Abstract Introduction: In recent years, due to the harmful effects of chemical food preservatives, consumers and food producers tend to use natural preservatives which in addition to increasing the shelf life of food to be safe from the harmful effects of chemical preservatives. Garlic plant has received a lot of attention due to the presence of many bioactive compounds, including allicin. Due to the instability of allicin, the use of this compound requires its encapsulation for food-pharmaceutical applications. Coacervation method is a promising technique for encapsulation, which is used in various industries including food and pharmaceutical industries. Among these, gelatin is the most common protein used in the complex coacervation process. Persian gum is a natural hydrocolloid that could potentially be used as alternative to natural but expensive microbial or plant hydrocolloids. The aim of this study was to encapsulated garlic extract by coacervation method in the gelatin - Persian gum biopolymer mixture. Material and method: First, the interaction between Persian gum and gelatin (from 2:0 to 1:1 ratio; total concentration of 2%) at pH range from 3 to 5 was investigated using the D-optimal statistical design. At this stage, turbidity tests, methylene blue adsorption, zeta potential measurement and rheological properties were performed on the treatments and the optimal treatment was obtained. Then FTIR and TGA tests as well as the morphology of the optimal treatment were examined. In the next step, 0 to 50 % concentrations of garlic extract were finely encapsulated in optimal treatment by coacervation method and its antioxidant and antimicrobial properties were investigated using DPPH, MIC and Disk Diffusion tests. Finally, the optimal treatment obtained from the previous steps was evaluated for FTIR tests, measuring size and zeta potential, as well as morphological characteristic. Result: The results of turbidity test showed a strong interaction between Persian gum and gelatin in 1:1 ratio and pH 4. The results of the FTIR test also confirmed this. The morphology of the biopolymer complex showed a spherical and dense structure. The average particle size was reported to be between 70-80 nm. Maximum coacervation yield was 58 %. The maximum antioxidant activity were observed in complex coacervate containing 50% garlic extract. When the concentration of garlic extract in the complex was 50%, the garlic extract showed the highest antimicrobial properties against Escherichia coli and Staphylococcus aureus.The interaction of the extract with biopolymers was confirmed by examining the results obtained from the absorption spectrum of FTIR. The morphology of the coacervate complex containing the extract was reported to be 49.69 to 90.64 nm. Conclusion: This study provides a better understanding of how the formation of gelatin-Persian gum coacervate complex and the introduction of a sustainable delivery system for bioactive compounds of garlic extract. Key words: Persian gum, gelatin, complex coacervation, Garlic extract